Conventional photographic film cassettes provide for storage of the unexposed film, and the unexposed film is then wound past a lens opening in a camera where it is exposed, and it is then usually rewound in the cassette, or in another portion of the cassette.
The cassette can then be removed from the camera, the cassette being light proof, and it then may be transferred to a laboratory for developing. Usually, the film must be removed from the cassette in substantially total darkness, in a darkroom, and transferred into some form of developing tank.
This procedure is prefectly acceptable for the great majority of photographic uses. However, in certain cases there may be no available access to a laboratory, and it may be desirable to produce developed film on the spot. There may be many situations in which this is desirable. For example, intelligence or security type film applications for collecting military intelligence, may find it especially useful to provide for immediate on the spot developing of an exposed piece of film.
Similarly, in many industrial applications, or in applications where for example inspections of a remote piece of equipment such as a pipe line or the like is carried out photographically, it may be desirable to provide for immediate on the spot developing of an exposed length of film.
These are only a few of many uses to which this type of requirement may be found to be especially useful. Clearly however there may be many other situations such as news photography sporting photography, and others which may also find such requirements especially advantageous.
One particular example where this proceedure is advantageous is in the field of geological explorations. Drill holes are usually drilled through ore bodies to determine the extent and orientation of a particular ore body. These drill holes may be many thousands of feed in length, and the drill bit itself may wander quite substantially from its true course. It is therefore essential to have an accurate plot of the exact path of the drill hole along its length so that the geological information collected from the drill hole may be correctly interpreted.
A great variety of instruments for logging the path or deviation of the bore hole has been proposed. However, one particularly advantageous instrument and method is disclosed in co-pending application Ser. No. 693,110 entitled "Bore Hole Probe" filed June 4, 1976, now U.S. Pat. No. 4,047,306.
In this system, a length of photographic film contained within the bore hole probe or logging instrument is exposed one frame at a time at for example twenty-five or fifty foot intervals down the bore hole. The deviation of a spot of light from the center of the film frame will give an accurate indication of the deviation of the path of the bore hole.
Such investigations are usually carried out many hundreds or thousands of miles from civilization, and in severe climatic conditions. Seldom is there any opportunity to arrange for photographic dark-room and laboratory facilities. However, it is highly desirable that the information collected from such exposed photographic film may be studied, at the drill site itself. Accordingly, the provision of a facility for developing the exposed photographic film, without the need for darkroom facilities, in this type of situation is especially advantageous.